Price of Marine Grade Steel in Asia

[mattplowman]

Can anyne give me a ballpark figure per kg for lets say ISO 10474 or equivalent in Asia?

am about to embark on self build and going to get the kit cut here in Asia......any thoughts / advice on this would be appreciated

cheers
Matt

[MikeJohns]

Probably going to be close to $2k AUD / tonne for you to buy 10 tonnes.
Steel prices are pretty variable at present and you would be best advised to shop around, given the regular freight services that use Singapore importing your steel would not be hard .

Were you going to build in Singapore?

Cheers

[mattplowman]

I am not sure yet - is going to be a home build but I live in a condo - so prob rent a space at a yacht club yard on east coast and go from there

2k AUD is $2.5k Sing - means for 17000kg it will be $42500 Sing Dollars which is a hell of allot better the the kit price quoted if cut and delivered by the designer - now just need to find out how much cnc cutting of 17000kgs of steel will cost me?

[MikeJohns]

Plasma cutters are small cheap resonably fast and very easy to use. If the lofting is simple you may be better off saving the CNC fee and employing some help.
cheers

[mattplowman]

its a radius chine hull and I have been told that it must be cut using CNC - the design I am buying comes with the cnc disk

[lazeyjack]

Originally Posted by mattplowman

its a radius chine hull and I have been told that it must be cut using CNC - the design I am buying comes with the cnc disk

17 tonnes? must be a bloody big boat you sure you don,t mean 17tonne disp?
nonsense abt cnc, you can open your files, and draw on your cutting lines

plasma is good for straight lines but for accurate cutting of curves I would use OXY PROPANE with a quality torch
And preblasted zinc painted to abt 75 microns dry film thickness is a very good idea cos believe you me, blasting an enclosed hull is expensive and hard work
good luck,

[lazeyjack]

did you already buy these plans?

[mattplowman]

have not brought the plans yet

kit weight after cutting is 17000kgs, displacement 25000, length 49ft

have been told by almost everyone that getting the KIT cut using CNC Plasma is the only way to get the accuracy?

cheers
Matt

[lazeyjack]

Originally Posted by mattplowman

have not brought the plans yet

kit weight after cutting is 17000kgs, displacement 25000, length 49ft

have been told by almost everyone that getting the KIT cut using CNC Plasma is the only way to get the accuracy?

cheers
Matt

i spose if you are not a boat builder then yes
thought abt alloy cheaper than steel overall, for given thickness one third the weight. that means if you are thickness for thickness(which you would not be) the material cost is same(roughly) but cost of finishing is much less, working it is easier faster cleaner

that is a big boat, why do you wnat such a boat, just cuirious)

[mattplowman]

have done most of my sailing on a 53ft Swan, love the size, know anything over 50 is to big for my budget so i figure 49 is alright!!

[MikeJohns]

The comparison of steel and alloy is interesting, in practice neither are greatly advantageous over the other, both can be excellent materials, there are generaly speaking far more pitfals in both the design and construction of alloy vessels.

Alloy is 1/3 the weight but when you look at the specific modulus it has only 1/3 the stiffness, In other-words it's stiffness to weight ratio is the same as mild steel. The result is that an alloy component 0.5 of the mass (1.5 times thickness) of a steel one will deflect twice as much even if it is the same "strength". This is why alloy decks often feel "soft".

Considering this stiffness issue, it is very important to design for alloy construction from scratch and you should never substitute alloy in a steel design. One of the big issues with this lower stiffness is a propensity to fatigue to failure, even more so in the weld zones. A lot of alloy boats are not sufficiently framed to prevent plating failure from flexure and we see a lot of this in recent work boat conversions where the plans have been switched from steel to alloy and only the yield strength is taken into account in the scantling changes.

Steel is so incredibly forgiving of amatuer construction and remains infinately repairable. I always urge home builders to get alloy hulls pro built and designed by someone who understands the material thoroughly. If you use scantlings based on steel and adjust to alloys strength you will get an early repair. We have been seeing this on some of the fast ferries. Some yacht hulls are definately inadequately stiffened and very poorly designed for alloy construction.

Finally if weight strength issues are predominant then Corten steel starts to look very attractive too at around 1.7 times stronger than mild steel..

As for CNC if you get the frames, transom, keel base cnc cut you don't need to do so with the plating, just use the traditional transferred pattern method.

[lazeyjack]

good post, but I never advised him to swap materials!!

i found alloy a lot easier, although I always maintained it took five years to make a good welder with alloy and over the years I never found different
i have to disagree, about sogginess mild steel/ alloy Most milds are just crap,
take forming a plate, mild si just so soft compared with 5083 h320, at least with alloy it comes with test certs, giving tensile etc, you never now what you are getting,with mild and the charecteristics are nothing like they should be, Corten, I love but not for amatuers
he could use a simple 2 chine yacht , a la francaise, and find a welder to glue it up

[lazeyjack]

i see your gallery what is your trade? Mike

[MikeJohns]

I'm a white haired irrascible pro engineer :-). Mainly commercial contract design, stability, corrosion, insurance and survey , a few yacht hull designs.

I have not had your experience with steel supplies, what grade are you ordering?